Pull Rod Release Mechanism for a Push-Pull Table Tool

ABSTRACT

In at least one embodiment, a table saw includes a table, a moveable carriage supported by the table, a saw assembly supported by the carriage, and a pull rod coupled to the carriage. The pull rod is configured to move in a linear direction relative to the housing between a back position and a forward position. The carriage and saw assembly move in the linear direction when the pull rod is moved in the linear direction. A collar is positioned on the pull rod and configured to move in the linear direction between a locked position and an unlocked position. The pull rod is configured to move in the linear direction from the back position toward the forward position when the collar is in the unlocked position, and the pull rod is blocked from moving from the back position when the collar is in the locked position.

This application is a divisional application of co-pending applicationSer. No. 12/821,884, filed on Jun. 23, 2010 (now U.S. Pat. No.8,474,358), the disclosure of such application which is totallyincorporated by reference herein in its entirety.

TECHNICAL FIELD

This disclosure relates to the field of to table-top power tool devicesoperated with pull rods, and to table top saws in particular.

BACKGROUND

Table-top power tools are used in a wide variety of applicationsincluding wood working and metal working. Table-top power tools aretypically mounted to a flat work surface, the table, configured toaccept and guide work piece to the table-top tool. These power toolsallow users to operate with more precision on larger work pieces thanallowed with hand-held power tools. While table-top power tools aremounted to the table, the angle and position of the tool may be adjustedduring operation. Some table-top power tools use one or more pull rodsto change the position of the table top tool.

An example of a table-top power tool using a pull rod is a table sawwhich includes a circular saw blade. The circular saw blade extendsthrough the table top surface, and a work piece, typically a piece ofwood, is placed on the table top for cutting. The saw blade assembly ismounted on rails running along the length of the table, and the sawblade may be pushed or pulled along the rails in response to pushing orpulling on the pull rod. If the saw is activated, the spinning saw bladecuts through work pieces placed in its path on the table. In someexisting table saws, the pull rod is also used to adjust the height ofthe circular saw blade. This adjustment is carried out by rotating thepull rod along its longitudinal axis in either a clockwise orcounter-clockwise direction. The rotation of the pull rod increases anddecreases the height of the saw blade above the table surface, dependingupon the direction of rotation of the pull rod.

The pull rod may also be configured to lock the blade in a fixedposition relative to table top in order to provide a rip saw mode ofoperation. In the rip saw mode, the pull rod locks the circular sawblade into a fixed position on the rails, and the work piece may then bemoved over the saw-blade to cut the work piece.

The pull rod may also be configured to lock itself and the circular sawblade in place to allow for safety and/or transportation of the tablesaw with the blade in a secured position. Existing pull rods that arelocked into position require two or more steps to unlock. For example,some known pull rod assemblies require a central button to be pushed inwhile simultaneously pulling outward on the pull rod to unlock it. Thesepull rod assemblies are generally difficult for an operator to unlock.

In view of the foregoing, it would be advantageous to provide a lockingand unlocking mechanism for a pull rod assembly that permits unlockingthe pull rod using fewer motions than traditional pull rod assemblies.It would also be advantageous to provide a locking and unlockingmechanism for a pull rod assembly configured to unlock the pull rodusing few motions while permitting the pull rod to rotate on itslongitudinal axis.

SUMMARY

In at least one embodiment, a table saw includes a table, a moveablecarriage supported by the table, a saw assembly supported by thecarriage, and a pull rod coupled to the carriage. The pull rod isconfigured to move in a linear direction relative to the housing betweena back position and a forward position. The carriage and saw assemblymove in the linear direction when the pull rod is moved in the lineardirection. A collar is positioned on the pull rod and configured to movein the linear direction between a locked position and an unlockedposition. The pull rod is configured to move in the linear directionfrom the back position toward the forward position when the collar is inthe unlocked position, and the pull rod is blocked from moving from theback position when the collar is in the locked position.

In at least one embodiment, a table saw includes a table, a moveablecarriage supported by the table, a saw assembly supported by thecarriage, and a pull rod coupled to the carriage. The pull rod isconfigured to move in a linear direction relative to the housing betweena back position and a forward position. The carriage and saw assemblymove in the linear direction when the pull rod is moved in the lineardirection, and a lock is configured to retain the pull rod in the backposition. The lock includes an actuator configured to move in the lineardirection between a locked position and an unlocked position. The pullrod is configured to move in the linear direction from the back positiontoward the forward position when the actuator is in the unlockedposition, and the pull rod is blocked from moving from the back positionwhen the actuator is in the locked position.

In at least one embodiment, a table tool with a retention mechanismincludes a table having a table top, a carriage assembly coupled to thetable top and movable in relation to the table top, and a pull rodassembly connected to the carriage assembly. The pull rod assembly isconfigured to move in a linear direction, and movement of the pull rodassembly in a linear direction results in movement of the carriageassembly in relation to the table top. The pull rod assembly includes apull rod, a detent movably supported by the pull rod and positionable ina blocking position and a recessed position, and a collar movablypositioned on the rod. The collar is engaged with the detent such thatmovement of the collar causes movement of the detent between theblocking position and the recessed position. The pull rod is inhibitedfrom moving in the linear direction in relation to the table top whenthe detent is in the blocking position, and the pull rod is allowed tomove in the linear direction in relation to the table top when thedetent is in the recessed position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an exploded view of an exemplary embodiment of a pull rodlocking mechanism having a collar as part of a pull rod handle.

FIG. 2 depicts a cross sectional view of the pull rod locking mechanismof FIG. 1 with a collar, detent, and pull rod in a locked position.

FIG. 3 depicts a cross sectional view of the pull rod locking mechanismof FIG. 1 with the collar and detent in an unlocked position.

FIG. 4 depicts a cross sectional view of the pull rod locking mechanismof FIG. 1 with the collar and detent in an unlocked position, and thepull rod partially disengaged from a table edge.

FIG. 5 depicts a cross sectional view of the pull rod locking mechanismof FIG. 1 with the collar and detent in a locked position and the pullrod disengaged from the table edge.

FIG. 6 depicts a cross sectional view of an embodiment of a pull rodlocking mechanism including a collar that slideably engages an interiorportion of a pull rod handle.

FIG. 7 depicts a cross sectional view of an embodiment of a pull rodlocking mechanism including a collar that slideably engages an exteriorportion of a pull rod handle.

FIG. 8 depicts a perspective view of a table saw using the pull rodassembly disclosed herein.

DETAILED DESCRIPTION OF THE DRAWINGS

For the purposes of promoting an understanding of the principles of theembodiments disclosed herein, reference will now be made to the drawingsand descriptions in the following written specification. It isunderstood that no limitation to the scope of the subject matter isthereby intended. It is further understood that the present disclosureincludes any alterations and modifications to the illustratedembodiments and includes further applications of the principles of thedisclosed embodiments as would normally occur to one skilled in the artto which this disclosure pertains.

Referring to FIG. 1, a pull rod assembly 100 includes a pull rod shaft104, collar 108, leaf spring 112 affixed to a detent 116, and handle128. A roll pin 120 engages through hole 110 in collar 108 to passthrough clearance slot 124. Roll pin 120 secures collar 108 to pull rodshaft 104, while allowing collar 108 a limited range of motion to slidealong a longitudinal axis of pull rod shaft 104 indicated by arrows 144and 148. In the embodiment of FIG. 1, collar 108 completely surroundspull rod shaft 104, but alternative collars may be semi-circular orU-shaped and surround only a portion of the pull rod shaft 104. Handle128 engages the end of pull rod shaft 104 via handle roll pin 132,enclosing leaf spring 112 and detent 116 within pull rod shaft 104. Aknob, seen here as pull rod handle 128, engages pull rod shaft 104 in afixed manner such that rotation of pull rod handle 128 causes rotationof pull rod shaft 104. Pull rod crank handle 140 is positioned in theproximity of an outer diameter of pull rod handle 128 to facilitatingclockwise or counterclockwise rotation of pull rod handle 128 and pullrod 104. Collar compression spring 136 surrounds pull rod shaft 104 andis affixed to pull rod handle 128 and collar 108.

Referring to FIG. 2, the pull rod assembly is seen in a locked positionthrough a side of a table housing 204 with pull rod shaft 216. In FIG. 2the pull rod assembly is in a back position at the maximum range ofmovement towards the interior of table housing 204. Pull rod shaft 216passes through a bushing 208 located at an opening through housing 204.Collar 236, handle 240, and crank handle 244 are positioned outsidebushing 208, while detent 224 engages a hole in pull rod shaft 216 onthe inside of bushing 208. Handle 240 is secured to pull rod shaft 216by handle roll pin 212.

In the embodiment of FIG. 2, detent 224 is a tapered button with abeveled leading edge 226. When pull rod shaft 216 is in the lockedposition of FIG. 2, detent 224 is positioned on the interior side ofhousing 204 and bushing 208. A lock actuator such as collar 236 is in alocked position with roll pin 228 at an end of clearance slot 232proximate to bushing 208. In this position, leaf spring 220 is in anextended position exerting a force in direction 256 urging detent 224into a blocking position through pull rod shaft 216. Collar 236 is seenin a locked position with pull rod handle 240, with collar compressionspring 248 in an extended position biasing collar 236 into the lockedposition. Collar compression spring is affixed at one end to collar 236and at another end to pull bar handle 240. When detent 224 is in thelocked position of FIG. 2, the pull rod assembly is locked to housing204. In the locked position, the detent 224 abuts the bushing 208 whenthe pull rod shaft 216 is urged in the direction of arrow 260, blockingthe pull rod shaft 216 from moving in the linear direction. Thus, thepull rod shaft 216 remains in the locked position in response to apulling force applied to handle 240 in direction 260. Pull rod shaft 216remains in the locked position, but is free to rotate in response toclockwise or counterclockwise forces exerted on handle 240 or crankhandle 244.

The pull rod assembly configuration of FIG. 2 with the detent in anunlocked position is shown in FIG. 3. Collar 236 is configured to bepulled away from housing 204 and bushing 208 in direction 360. In theconfiguration of FIG. 3, collar 236 is displaced towards handle 240 inan unlocked position, compressing collar compression spring 248. Whenthe collar 236 is moved in direction 360, roll pin 228 is also displacedin direction 360 to a position at an end of clearance slot 232 that isdistal to bushing 208. Movement of the roll pin 228 to this positioncompresses leaf spring 220 in direction 356. Leaf spring 220 compressesin direction 356, such that detent 224 is moved in direction 356 to arecessed position with respect to detent button hole 316 disposed inpull rod shaft 216. Thus, roll pin 228 slideably engages leaf spring 220when collar 236 is moved in direction 360. If a force pulling collar 236in direction 360 is released, collar compression spring 248 urges collar236 to return the position depicted in FIG. 2.

In the configuration of FIG. 3, pull rod shaft 216 is unlocked, movingdetent 224 out of an intersection path with bushing 208 and allowingpull rod shaft 216 to travel in direction 364 in response to a pullingforce applied to handle 240. Additionally, in the unlocked position,pull rod shaft 216 may rotate in response to a clockwise orcounterclockwise force exerted on handle 240 via crank handle 244.

The pull rod assembly of FIG. 3 is seen in a partially extended positionin FIG. 4 (i.e. between a back position and a forward position). In FIG.4, pull rod shaft 216, leaf spring 220, detent 224, collar 236, pull rodhandle 240, and crank handle 244 are displaced away from housing 204toward a forward position in direction 460. Collar 236 is in an unlockedposition pulled towards handle 240, compressing collar compressionspring 248. Roll pin 228 is at the position at the end of clearance slot232 that is distal to bushing 208. In the example of FIG. 4, roll pin228 compresses leaf spring 220 in direction 456, which in turn removesdetent 224 from detent button hole 316. In the position of FIG. 4, ifcollar 236 is released, allowing collar compression spring 248 to expandin direction 464 and move roll pin 228 in direction 464, beveled detentedge 226 may alternatively engage bushing 208. When engaged to bushing208 in this manner, detent 224 and pull rod shaft 216 may travel ineither direction 460 or 464. Thus, in the configuration of FIG. 4, pullrod shaft 216 is free to slide either away from housing 204 in direction460, or towards housing 204 in direction 464, regardless of the positionof collar 236. Pull rod shaft 216 is also free to rotate in response toa clockwise or counterclockwise force exerted on handle 240 or crankhandle 244.

The pull rod assembly of FIG. 4 with a locking mechanism fullydisengaged from the table housing is seen in FIG. 5. Collar compressionspring 248 is in an extended position, with roll pin 228 positioned atan end of clearance slot 232 proximate to bushing 208. Leaf spring 220urges detent 224 through pull rod shaft 216. In the configuration ofFIG. 5, pull rod shaft 216 is free to move in either direction 560 or564. Pull rod shaft may move in direction 560 toward a forward positionfor a predefined distance that is determined by the intended range ofmotion of the table saw. Pull rod shaft 216 is also free to rotate inresponse to a clockwise or counterclockwise force exerted on handle 240or crank handle 244.

With continued reference to FIG. 5, if pull rod shaft 216 is moved indirection 564, beveled edge 226 of tapered detent 224 engages bushing208, and detent 224 is displaced to the interior of pull rod 216, towardthe recessed position. If the motion continues in direction 564, detent224 is moved past the inner circumference of bushing 208, allowingdetent 224 to slide along the inner surface of bushing 208. Furthercontinued movement in the direction 564 moves the detent 224 past therear edge of bushing 208 and locks the pull rod shaft 216 in theconfiguration seen in FIG. 2. In this manner, pull rod shaft 216 may belocked by pushing handle 240 in direction 564 until handle 240 contactsbushing 208 as seen in FIG. 2. Accordingly, there is no need for theuser to pull the collar 236 to return the pull rod to the lockedposition.

Referring to FIG. 6, an embodiment of a pull rod assembly with a collarconfigured to engage an interior portion of a pull rod handle is shown.Collar 636 has an outer surface having a diameter narrower than that ofpull rod handle 628. When pulled in direction 660, collar 636 moves tothe interior of pull rod handle 628. An alternative to the embodiment ofFIG. 6 is the pull rod assembly of FIG. 7. In FIG. 7, collar 736 has aninner surface engaging an outer surface of pull rod handle 728. Whenpulled in direction 760, collar 736 moves over the exterior of pull rodhandle 728. Both of the embodiments of FIG. 6 and FIG. 7 are suitablefor operation with the pull rod assemblies depicted in FIG. 1-FIG. 5.

A push-pull table saw employing the pull rod locking assembly discussedabove is depicted in FIG. 8. Table saw 800 includes a table surface 804,circular saw blade 808, blade guard 812, carriage 814, and table housing816. Bushing 820 extends from table housing 816 with a pull rodextending through bushing 820, collar 824, and pull rod handle 828. Inthe configuration of FIG. 8, the pull rod is in a locked position. A sawoperator may unlock the pull rod assembly by pulling pull rod handle 828in direction 860 while squeezing collar 824 toward pull rod handle 828in direction 860. Once unlocked from housing 816, the pull rod pulls acarriage 814, which is supported by, and may slide over, guide rods ortracks beneath table surface 804. Carriage 814 supports blade 808 andblade guard 812, which move in direction 860 along blade track 810. Alsoonce unlocked, pull rod handle 812 may be rotated in a clockwise orcounterclockwise direction using crank handle 832. This rotation adjuststhe height of saw blade 808 and blade guard 812 above table surface 804.A work piece, such as a piece of wood, placed in blade path 810 is cutby rotating circular blade 808. In the embodiment of FIG. 8, the degreeof linear motion of blade 808 and blade guard 812 in direction 860 isthe same as the degree of linear motion of carriage 814 and pull rodhandle 828 in direction 860.

The saw 800 of FIG. 8 may be locked by returning the pull rod assemblyto the position depicted in FIG. 8. A return spring 815 operativelyconnected to the carriage 814 and the table housing 816 urges thecarriage 814 and the pull rod including pull rod handle 828 and collar824 towards the locked position in direction 864. Once locked, saw blade808 and blade guard 812 are prevented from moving in direction 860. Sawblade 808, blade guard 812, and carriage 814 are locked automaticallywhen the operator releases the pull rod, allowing the return spring 815to return the saw 800 to the locked position depicted in FIG. 8.Alternatively, an operator may also push the pull rod handle 828 indirection 864 until the pull rod assembly locks in place with housing816.

In a locked mode of operation a pull rod in a table top power tool isprevented from sliding in a linear direction by a locking detentdisposed within a housing of a table. The locked pull rod may rotate ina clockwise or counterclockwise direction to further adjust the tabletop power tool. The pull rod assembly may be unlocked by an operatorsqueezing the collar against the pull rod handle while pulling the pullrod handle away from the housing in a linear direction matching thedirection of movement of the table top tool. This motion continues untilthe locking detent button moves past the interior of the table housing,at which point the collar may be released.

In an unlocked mode of operation, a pull rod assembly may travel alinear direction toward or away from a housing of a table. A power toolsuch as a circular saw may move in response to movement of the pull rod.The unlocked pull rod may also rotate in a clockwise or counterclockwisedirection to further adjust the position of the table top power tool.Upon the pull rod being released, a return spring urges carriage and theunlocked pull rod to return to the locked position with the detentinside of the housing. The detent button locks automatically with thedetent button hole disposed inside the housing. The operator can releasethe pull rod any distance from the locked position during pulling andthe carriage will retract automatically to the home back locked positionIn one embodiment, the pull rod handle contacts a bushing disposed onthe exterior of the table housing when in the locked position.

The foregoing pull rod assembly has advantages over existing pull rodmechanisms. One advantage is that the pull rod may be unlocked by anoperator by squeezing the collar and the pull rod handle togetherinstead of requiring a more complex unlocking procedure. Anotheradvantage is that, once unlocked, the pull rod returns to a lockedposition and the carriage is locked automatically when the pull rod isreleased by an operator.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same should be considered asillustrative and not restrictive in character. For example, while thedisclosed embodiments are directed to a table saw, other table top toolsincluding drill presses or lathes may be modified to use the pull rodlocking assembly disclosed above. It is understood that only thepreferred embodiments have been presented and that all changes,modifications and further applications that come within the spirit ofthe invention are desired to be protected.

What is claimed is:
 1. A table tool with a retention mechanismcomprising: a table having a table top; a carriage assembly coupled tothe table top and movable in relation to the table top; a pull rodassembly connected to the carriage assembly, the pull rod assemblyconfigured to move in a linear direction, wherein movement of the pullrod assembly in a linear direction results in movement of the carriageassembly in relation to the table top, the pull rod assembly comprising:a pull rod; a detent movably supported by the pull rod and positionablein a blocking position and a recessed position; and a collar movablypositioned on the rod, wherein the collar is engaged with the detentsuch that movement of the collar causes movement of the detent betweenthe blocking position and the recessed position; wherein the pull rod isinhibited from moving in the linear direction relation to the table topwhen the detent is in the blocking position, and wherein the pull rod isallowed to move in the linear direction in relation to the table topwhen the detent is in the recessed position.
 2. The table tool of claim1 further comprising: a bushing connected to the table, the bushinghaving an interior side and an exterior side, and the pull rod extendingthrough the bushing; a button hole formed in a portion of the rod withthe detent positioned in the button hole.
 3. The table tool of claim 1wherein the detent further comprises a leaf spring and a detent button,the detent button attached to the leaf spring, wherein the detent is inthe blocking position when the detent button is in an extended positionin the button hole and the button hole is positioned on the interiorside of the bushing.
 4. The table tool of claim 3 further comprising aroll pin connected to the collar and engaging the leaf spring; the rollpin configured to move the leaf spring such that the detent button ismoved to a recessed position in the button hole when the collar is movedin the linear direction away from the bushing; and the roll pinconfigured to allow the leaf spring to return the detent button to theextended position when the collar is moved in the linear directiontowards the bushing.
 5. The work tool of claim 3 wherein the detentbutton is a tapered detent button.
 6. The work tool of claim 5 whereinthe tapered detent button includes a beveled edge configured to engagethe exterior side of the bushing and urge the detent button towards therecessed position when the collar is moved in the linear directiontowards the bushing.
 7. The work tool with a retention mechanism ofclaim 1 wherein the carriage assembly further comprises: a saw blade anda motor configured to rotate the saw blade.